Distributing power between data centers

ABSTRACT

A data center operable using only electric power based on renewable energy. The data center includes at least one device driven by the electric power, a storage battery for storing the electric power, and a controller for switching the operating mode of the device over the course of time on the basis of predicted values for the amount of electric power generated using renewable energy, the amount of electric power stored in the storage battery, and the amount of electric power consumed by the device.

BACKGROUND

The present invention relates to a data center and, more specifically,to a method for distributing a load between data centers that areoperable using only electric power based on renewable energy.

When a data center is operated using electric power generated fromrenewable energy such as wind power or solar power, the supply ofelectric power to the data center is not always stable. Therefore,hardly any data centers rely exclusively on renewable energy at thepresent time. For example, some data centers use some power generatedphotovoltaically but draw the remaining demand from ordinarytransmission lines. In other words, data centers currently cannotoperate exclusively on electric power based on renewable energy.

There are examples of data centers drawing all of their electric powerfrom photovoltaic cells but, in order to provide a constant supply ofphotovoltaically generated electric power to a data center given theinstability of available sunlight, a large (excess) number of solarpanels and storage batteries is required, which makes installation costshigher than they would otherwise be. When considering the installationof a data center in a location without transmission lines, there isconcern over the inability to supply electric power to the data centerfrom the grid in an emergency.

A terminal device/information processing system is disclosed inlaid-open patent publication JP2012-058837 to O. Atsushi, titled“Terminal Device, Information Processing System, Request DestinationSelection Method, and Program” which includes a selection unit forselecting an external device connected to a processing unit orconnecting unit as the device to process a given request depending uponthe circumstances, a power storage unit for storing electric power usedto operate the processing unit, and a power level detecting unit fordetecting the amount of electric power stored in the power storage unit.In this system, the selection unit selects an external device connectedvia a connecting unit when the power level detected by the power leveldetecting unit has fallen below a predetermined value. However, theinvention disclosed in JP2012-058837 does not relate to a data center orto a method for distributing the load between data centers operableusing only electric power based on renewable energy.

SUMMARY

Therefore, it is an object of the present invention to enable the steadyexecution of jobs to be processed while predicting the amount ofelectric power being supplied to data centers operable using onlyelectric power based on renewable energy. It is another object of thepresent invention to properly share and stably execute jobs to beprocessed between data centers while predicting the amount of electricpower being supplied to each data center.

One aspect of the present invention is a data center operable using onlyelectric power based on renewable energy. This data center includes: atleast one device driven by the electric power; a storage battery forstoring the electric power; and a controller for switching the operatingmode of the device over the course of time on the basis of predictedvalues for the amount of electric power generated using renewableenergy, the amount of electric power stored in the storage battery, andthe amount of electric power consumed by the device.

Because, in an aspect of the present invention, the operating mode ofthe device is switched over the course of time on the basis of predictedvalues for the amount of electric power generated using renewableenergy, the amount of electric power stored in the storage battery, andthe amount of electric power consumed by the device, operation of thedevice is able to remain stable relative to changes in the amount ofelectric power being supplied.

In an aspect of the present invention, the controller determines thepredicted value B(T) for the amount of electric power stored in thestorage battery at time T on the basis of the following formula:

B(T)=B(0)+∫(g(t)−c(t))dt

where g(t) is the amount of electric power generated by the renewableenergy, and c(t) is the amount of electric power consumed by the device.

Therefore, in an aspect of the present invention, the predicted valueB(T) for the amount of electric power stored in the storage battery attime T can be predicted and stable power can be supplied to the datacenter in the future.

In an aspect of the present invention, the controller switches theoperating mode of the device to the power saving mode at time T1 atwhich the predicted value B(T) for the amount of electric power storedin the storage battery is lower than predetermined threshold value Bth.

Therefore, in an aspect of the present invention, the operation of thedevice can be maintained at a minimum level to wait for an increase inthe amount of generated power stored in the storage battery when theamount of electric power stored in the storage battery is low.

In an aspect of the present invention, the controller determines thepredicted value g(t) for the amount of electric power generated usingrenewable energy on the basis of weather forecast data at time t whenthe amount of electric power generated using renewable energy changes inresponse to weather conditions in the region including the location ofpower generation.

Therefore, in an aspect of the present invention, power can be suppliedstably and continuously to the data center based on a prediction of theamount of electric power stored in the storage battery even when theamount of electric power generated changes due to weather conditions.

In an aspect of the present invention, the electric power generatedusing renewable energy is supplied by solar power and/or wind power.

Therefore, in an aspect of the present invention, power can be suppliedstably and continuously to the data center based on a prediction of theamount of electric power stored in the storage battery even when theamount of wind or solar power generated changes due to weatherconditions.

One aspect of the present invention is a method for distributing a loadbetween data centers. In this method, each data center is connected toenable communication and is operable using electric power based only onrenewable energy, and includes at least one server driven by electricpower, and a storage battery for storing the electric power. In thismethod, at least one server at a data center executes the method, whichincludes the steps of: acquiring a predicted value for the amount ofelectric power stored in the storage battery at each data center; andassigning servers to execute jobs to be processed by each of the serversat the data center in response to the predicted value for the amount ofstored power.

Therefore, in an aspect of the present invention, jobs to be processedcan be assigned in a flexible and timely manner to data centers operableusing only electric power based on renewable energy in response to thepredicted values for the amount of electric power stored in the storagebatteries at the data centers.

In an aspect of the present invention, the step of assigning serversalso includes the step of assigning servers to execute jobs indescending order from servers at the data center with the highestpredicted value for the amount of stored power. Also, when jobs areassigned to servers, jobs are assigned to servers at data centers with apredicted value for the amount of electric power stored that exceeds apredetermined threshold value.

Therefore, in an aspect of the present invention, servers with asufficient supply of power can be selected and jobs to be processed canbe performed stably and reliably.

In an aspect of the present invention, the step of assigning serversalso includes the step of switching the operating mode of servers and/orother devices to power saving mode at a data center, if the predictedvalue for the amount of electric power stored is lower than apredetermined threshold value.

Therefore, in an aspect of the present invention, the operation ofservers and device can be maintained at a minimum level to wait for anincrease in the amount of generated power stored in the storage batterywhen the amount of electric power stored in the storage battery is low.

In an aspect of the present invention, the predicted value B(T) for theamount of electric power stored in the storage battery at time T isdetermined on the basis of the following formula:

B(T)=B(0)+∫(g(t)−c(t))dt

where g(t) is the amount of electric power generated by the renewableenergy, and c(t) is the amount of electric power consumed by the device.

Therefore, in an aspect of the present invention, the predicted valueB(T) for the amount of electric power stored in the storage battery attime T can be predicted and stable power can be supplied to the datacenter in the future.

In an aspect of the present invention, the step of assigning serversalso includes the step of assigning a job to a server at another datacenter from a server having at time T1 a predicted value B(T) for theamount of electric power stored in the storage battery that is lowerthan predetermined threshold value Bth.

Therefore, in an aspect of the present invention, at a time at whichlower levels of power stored in storage batteries is predicted, jobs tobe processed can be stably and continuously processed by servers atother data centers with a high level of power stored in their storagebatteries.

In an aspect of the present invention, the predicted value g(t) for theamount of electric power generated using renewable energy is determinedon the basis of weather forecast data at time t when the amount ofelectric power generated using renewable energy changes in response toweather conditions in the region including the location of powergeneration.

Therefore, in an aspect of the present invention, jobs to be processedcan be assigned to the appropriate data center based on a prediction ofthe amount of electric power stored in the storage battery even when theamount of electric power generated changes due to weather conditions.

In an aspect of the present invention, the electric power generatedusing renewable energy is supplied by solar power and/or wind power.

Therefore, in an aspect of the present invention, jobs can be assignedto the appropriate data center based on a prediction of the amount ofelectric power stored in the storage battery even when the amount ofwind or solar power generated changes due to weather conditions.

In an aspect of the present invention, the step of assigning serversalso includes the step of selecting a data center for a job assignmenton the basis of the regional time difference between data centers whenthe electric power generated using renewable energy is supplied by solarpower.

Therefore, in an aspect of the present invention, time differences canbe taken into account to select data centers in regions where power isbeing generated photovoltaically, and assign jobs to be processed toservers at these data centers on a rolling basis. As a result, jobs canbe stably executed and monitored over a twenty-four hour period.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a diagram showing a configuration example of a data centernetwork system according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration example of a single datacenter according to an embodiment of the present invention.

FIG. 3 is a diagram showing a configuration example of a managementserver according to an embodiment of the present invention.

FIG. 4 is a diagram showing the operational flow in a method accordingto an embodiment of the present invention.

FIG. 5 is a diagram showing an example of predictions such as the amountof stored power according to an embodiment of the present invention.

FIG. 6 is a diagram showing the operational flow in a method accordingto an embodiment of the present invention.

FIG. 7 is a diagram showing an example of predicting the amount ofstored power according to an embodiment of the present invention.

DETAILED DESCRIPTION

The following is an explanation of an embodiment of the presentinvention with reference to the drawings. FIG. 1 is a diagram showing aconfiguration example of a data center network system according to anembodiment of the present invention. The network system 100 includes acommunication network 10, four data centers (A-D) 20-26 in thecommunication network 10, and computers (terminals) 30, 32 that can beconnected to the communication network 10. Each data center computer cancommunicate with other data centers and computers (terminals). Thecommunication paths in FIG. 1 are denoted by the dotted lines. Thesecommunication paths can be wired or wireless communication paths. Thenumber of data centers and terminals shown in FIG. 1 is just an example,and the scale of the network system can be increased or decreased.

FIG. 2 is a diagram showing a configuration example of one of the datacenters 20-26 in FIG. 1. Each data center includes a management server200, a controller 210, an ICT device 220, a power generator 230, abattery charger 240, and a storage battery 250. The management server200 can be any type of server, such as a web server or DNS server. Inthe following explanation, the management server is sometimes referredto simply as the “server.” The load on the management server 200 (powerconsumption, jobs) is monitored, and data is sent to the controller 210.The controller 210 includes control functions for executing the methodof an embodiment of the present invention, and can constitute some ofthe functions performed by the management server 200. The controlfunctions of the controller 210 include server load balancing fordistributing the load between servers, and so-called web switching. Thecontrol functions of the controller 210 are described below.

The ICT device 220 is used for processing information and forcommunication. This may include a computer device such as a server, anda storage device (such as an HDD) or tape drive. In an embodiment of thepresent invention, lighting and air conditioning equipment are alsoincluded. The load on the ICT device 220 (power consumption, etc.) ismonitored, and data is sent to the controller 210. The power generator230 is a device or system installed at each data center. In anembodiment of the present embodiment, it includes a power generatingsystem using renewable or natural energy such as solar power and/or windpower. The power generator 230 includes a function (sensors, etc.) formonitoring fluctuations in the amount of electric power being generatedover time, and sending data related to the amount of electric powerbeing generated to the controller 210. The controller 210 is configuredto receive weather forecast data in order to predict the amount ofelectric power that will be generated by the power generating systemusing renewable energy.

The battery charger 240 charges the storage battery used by the server,the ICT device, and the other devices with electric power from the powergenerator 230. The storage battery 250 stores power generated by thepower generator 230, and supplies stored power to the server, the ICTdevice, and the other devices. The capacity of the storage battery 250enables the server, the ICT device, and the other devices to operate fora predetermined amount of time using only its capacity (maximum powerstorage capacity). The storage battery 250 includes a function formonitoring the level of stored power (using sensors, etc.), and sendingdata on the level of stored power to the controller 210. In FIG. 2, thebattery charger 240 and the storage battery 250 are separate units.However, an all-in-one charger/storage device can also be used.

FIG. 3 is a block diagram showing a configuration example of the server200 in an embodiment of the present invention. The server in FIG. 3 is ahost (main computer). The computer includes an arithmetic processingdevice (CPU) 300, a storage means 310, and various types of interfaces(I/F) 320 connected to each other via a bus 330. Types of interfaces 320generally include input interfaces, output interfaces, external storageinterfaces, and external communication interfaces. These interfaces areconnected, for example, to an input means 340 such as a keyboard andmouse, a display means 350 such as a CRT or LCD, communication means360, and an external storage means 370 such as a USB-connectedsemiconductor memory or HDD. The storage means 310 can includesemiconductor memory such as a RAM and ROM, and an HDD.

The following is an explanation of an embodiment of the presentinvention with reference to FIG. 4 through FIG. 6. FIG. 4 and FIG. 6 arediagrams showing the operational flow in the method of an embodiment ofthe present invention. FIG. 5 and FIG. 7 are diagrams showing examplesof prediction graphs for the amount of electric power stored in thestorage battery of an embodiment of the present invention. Theoperational flow in FIG. 4 and FIG. 6 can be executed by the controller210 in the configuration shown in FIG. 2 and can be one of the controlfunctions of the controller 210 in a data center.

In Step S11 of FIG. 4, the current power level B(T0) of the storagebattery 250 is detected (monitored). In Step S12, it is determinedwhether or not the current power level B(T0) is equal to or greater thana predetermined threshold value Bth_(—)1(T0). If NO, the operating modeof the ICT device in the data center is switched to conservation (powersaving) mode in Step S13. In this way, the rate of decline in the amountof electric power stored in the storage battery 250 can be slowed.

In Step S14, the current power level B(T0)′ of the storage battery isagain detected (monitored) after a predetermined amount of time haselapsed (for example, 5 to 10 minutes). In Step S15, it is determinedwhether or not the current power level B(T0)′ is less than or equal to apredetermined threshold value Bth_(—)2(T0). If YES, the ICT device inthe data center is turned off in Step S16. In this way, the decline inthe amount of electric power stored in the storage battery 250 isreduced to zero. When the determination in Step S15 is NO, it isdetermined in Step S17 whether or not the current power level B(T0)′ isequal to or greater than a predetermined threshold value Bth_(—)3(T0).If YES, the ICT device is released from conservation (power saving) modeand switched to normal operating mode in Step S18.

When the determination in Step S12 is YES, the level of stored powerB(T1) in the storage battery 250 is calculated in Step S19 after apredetermined period of time T1 has elapsed (for example, 1 or 2 hours).The level of stored power B(T1) is calculated as a single predictedvalue. The calculation is performed using Equation (1) below.

B(T1)=B(T0)+∫_(T0) ^(T1[) g(t)dt−c(t)]dt   (1)

where:

-   B(T1): Amount of electric power stored in the storage battery at    time T1-   B(T0): Amount of electric power stored in the storage battery at    time T0-   g(t): Power generated by the power generator-   c(t): Power consumed by devices, etc. at the data center.

In Equation (1), B(T0) is the value calculated in Step S11. Also, c(t)is determined as the predicted value for the amount of electric powerconsumed by devices, etc. at given time t between times T0 and T1.Similarly, g(t) is determined as the predicted value for the amount ofelectric power generated by the power generator at given time t betweentimes T0 and T1. When the power generator is a power generating systemusing renewable energy such as solar power or wind power, the amount ofelectric power generated changes depending on the weather conditions inthe region including the location of the power generator. Therefore, asimulation is run based on weather forecast information to determine theamount of electric power generated at the location or in the region ofthe power generator.

FIG. 5 is an example graph showing the change in predicted values c(t),g(t) and B(t) every hour from time T0 (0 hours) to time T1 after 7hours. Each predicted value is a percentage (%), with the minimum valuebeing 0%, and the maximum value being 100%. In FIG. 5, the amount ofstored power B(t) declines sharply over the first two hours, andcontinues to decline until four hours has passed. However, because theamount of electric power c(t) consumed by the devices, etc. remainsfairly constant, the amount of stored power B(t) can be predicted torecover (increase) after four hours as the amount of electric powergenerated g(t) increases.

Returning to FIG. 4, it is determined in Step S20 whether or not thecalculated amount of stored power B(T1) is equal to or greater than apredetermined threshold value Bth_(—)1(T1). If NO, the operating mode ofthe ICT device in the data center is switched to conservation (powersaving) mode in Step S13. Afterwards, Step S14 and the subsequent stepsdescribed above are executed.

Threshold value Bth_(—)1(T0) in Step S12, threshold value Bth_(—)2(T0)in Step S15, threshold value Bth_(—)3(T0) in Step S17, and thresholdvalue Bth_(—)1(T1) in Step S20 of FIG. 4 are established in accordancewith a prediction graph created for each data center such as the oneshown in FIG. 5 so that power can be supplied stably from the amount ofelectric power stored in the storage battery without having to turn offany of the devices if at all possible. In the example prediction graphshown in FIG. 5, threshold value Bth_(—)1(T0) can be set to 40%,threshold value Bth_(—)2(T0) to 10%, threshold value Bth_(—)3(T0) to60%, and threshold value Bth_(—)1(T1) to 40%.

FIG. 6 is a diagram showing the operational flow in an embodiment of amethod of an embodiment of the present invention for distributing theload among data centers. In Step S31 of FIG. 6, the amount of storedpower B(T) in a data center at current or future time T is acquired. Theamount of stored power B(T) at future time T is obtained as a predictionvalue calculated using Equation (1) above. At this time, the amount ofstored power B(T) at other data centers is acquired in the same manner,and the information is collected at a single data center.

In Step S32, it is determined whether or not the amount of stored powerB(T) is equal to or greater than a predetermined threshold valueBth_(—)1(T). If NO, the operating mode of the ICT device in the datacenter is switched to conservation (power saving) mode in Step S33.Next, in Step S34, it is determined whether or not any of the other datacenters is a data center DC_x with an amount of stored power B(T) equalto or greater than threshold value Bth_(—)1(T). If NO, the processadvances to Step S14 in FIG. 4 and this step and subsequent steps areexecuted.

When the determination in Step S34 is YES, it is determined in Step S35whether or not data center DC_x is to be assigned as the data center toexecute a job to be processed at time T. In other words, the job is tobe executed by a server in data center DC_x at time T. When, as a resultof the determination performed in Step S34, two or more data centersDC_x are potential candidates, the data centers are assigned indescending order from the data center with the highest predicted valuefor the amount of stored power B(T).

FIG. 7 is a diagram showing an example of predicting the amount ofstored power B(T) at three data centers A, B, C. Data centers A, B and Ccan correspond to data centers A, B and C in the communication network10 shown in FIG. 1. FIG. 7 shows the predicted value (%) for the amountof stored power B(T) per hour from time T0 (0 hours) to time T1, whichis seven hours later.

In FIG. 7, when threshold value Bth_(—)1(T) is, for example, 40%, thepredicted value for the amount of stored power B(T) at data center C isbelow threshold value Bth_(—)1(T) for the first three hours. Therefore,jobs that should be processed by a server at data center C are processedinstead by servers at data center A or data center B which have apredicted value for the amount of stored power B(T) that is equal to orgreater than the threshold value Bth_(—)1(T). At this time, data centerA is selected as the first data center to perform the processing becauseit has the higher predicted value for the amount of stored power B(T).

In FIG. 7, the predicted value for the amount of stored power B(T) atdata center A declines after four hours and falls below the thresholdvalue Bth_(—)1(T) of 40%. Therefore, jobs that should be processed by aserver at data center A are processed instead by servers at data centerB or data center C which have a predicted value for the amount of storedpower B(T) that is equal to or greater than the threshold valueBth_(—)1(T).

When data centers A-C are selected (assigned) in this manner, datacenters that are supplied power from renewable energy such as solarpower can be selected for assignment while taking into account regionaltime differences between data centers. When there are four data centersas in the example shown in FIG. 1, data centers using solar power can beselected in the order A→C→B→D during daylight hours at the variouslocations, and servers to process jobs can be selected according to thetime difference. In this way, jobs can be stably executed and monitoredover a twenty-four hour period.

In this way, a method of an embodiment of the present invention is ableto predict the level of stored power B(T) at each data center, andselect the data center with the highest level of stored power B(T) forjob assignment. As a result, the stable and continuous execution of jobscan be ensured even by data centers operated exclusively by powergenerating systems using renewable energy such as solar power and windpower.

The operational flow shown in FIG. 6 can be executed by a server loadbalancer (SLB, GSLB) used to distribute the load among servers. In anexplanation using the configuration shown in FIG. 1 and FIG. 2, theserver 200 is a DNS server and performs the following process. In thisexample, the level of stored power at data center C is the highest.

(1) Clients (terminals 30, 32) query the DNS server at data center A fora domain name.

(2) The DNS server at data center A passes on the query to a DNS serverat Company X (data center B).

(3) The DNS server at Company X returns a virtual IP (VIP) address atdata center C to the DNS server at data center A in accordance with aGLSB algorithm.

(4) The clients (terminals 30, 32) access the VIP address at data centerC.

The present invention was explained above using an embodiment, but thetechnical scope of the present invention is not limited to theembodiment described above. The possibility of many modifications andimprovements to this embodiment should be apparent to those skilled inthe art, and any embodiments including these modifications andimprovements are within the technical scope of the present invention.

What is claimed is:
 1. A data center operable using only electric powerbased on renewable energy, the data center comprising: at least onedevice driven by the electric power; a storage battery for storing theelectric power; and a controller for switching the operating mode of thedevice over the course of time on the basis of predicted values for theamount of electric power generated using renewable energy, the amount ofelectric power stored in the storage battery, and the amount of electricpower consumed by the device.
 2. The data center according to claim 1,wherein the controller determines the predicted value B(T) for theamount of electric power stored in the storage battery at time T on thebasis of the following formula:B(T)=B(0)+∫(g(t)−c(t))dt where g(t) is the amount of electric powergenerated by the renewable energy, and c(t) is the amount of electricpower consumed by the device.
 3. The data center according to claim 2,wherein the controller switches the operating mode of the device to thepower saving mode at time T1 having a predicted value B(T) for theamount of electric power stored in the storage battery lower thanpredetermined threshold value Bth.
 4. The data center according to claim2, wherein the controller determines the predicted value g(t) for theamount of electric power generated using renewable energy on the basisof weather forecast data at time t when the amount of electric powergenerated using renewable energy changes in response to weatherconditions in the region including the location of power generation. 5.The data center according to claim 4, wherein the electric powergenerated using renewable energy is supplied by solar power and/or windpower.
 6. A method for distributing a load between data centers, eachdata center being communicably connected, operable using electric powerbased only on renewable energy, and including at least one server drivenby electric power, and a storage battery for storing the electric power,and at least one server at a data center executing the method, themethod comprising the steps of: receiving a predicted value for theamount of electric power stored in the storage battery at each datacenter; and assigning servers to execute jobs to be processed by each ofthe servers at the data center in response to the predicted value forthe amount of stored power.
 7. The method according to claim 6, whereinthe step of assigning servers further comprises the step of assigningservers to execute jobs in descending order from servers at the datacenter with the highest predicted value for the amount of stored power.8. The method according to claim 6 or claim 7, wherein the step ofassigning servers further comprises the step of assigning a job toservers at the data center having a predicted value for the amount ofelectric power stored exceeding a predetermined threshold value.
 9. Themethod according to claim 8, wherein the step of assigning serversfurther comprises the step of switching the operating mode of a serverand/or other device to power saving mode at a data center, if thepredicted value for the amount of electric power stored is lower than apredetermined threshold value.
 10. The method according to claim 6,wherein the predicted value B(T) for the amount of electric power storedin the storage battery at time T is determined on the basis of thefollowing formula:B(T)=B(0)+∫(g(t)−c(t))dt where g(t) is the amount of electric powergenerated by the renewable energy, and c(t) is the amount of electricpower consumed by the device.
 11. The method according to claim 10,wherein the step of assigning servers further comprises the step ofassigning a job to a server at another data center from a server havingat time T1 a predicted value B(T) for the amount of electric powerstored in the storage battery that is lower than predetermined thresholdvalue Bth.
 12. The method according to claim 10, wherein the predictedvalue g(t) for the amount of electric power generated using renewableenergy is determined on the basis of weather forecast data at time twhen the amount of electric power generated using renewable energychanges in response to weather conditions in the region including thelocation of power generation.
 13. The method according to claim 12,wherein the amount of electric power generated using renewable energy issupplied by solar power and/or wind power.
 14. The method according toclaim 6, wherein the step of assigning servers further comprises thestep of selecting a data center for a job assignment on the basis of theregional time difference between data centers when the electric powergenerated using renewable energy is supplied by solar power.
 15. Acomputer program product for distributing a load between data centers,each data center being communicably connected, operable using electricpower based only on renewable energy, and including at least one serverdriven by electric power, and a storage battery for storing the electricpower, the computer program product comprising: one or morecomputer-readable storage media and program instructions stored on theone or more computer-readable storage media, the program instructionscomprising: program instructions to receiving a predicted value for theamount of electric power stored in the storage battery at each datacenter; and program instructions to assign servers to execute jobs to beprocessed by each of the servers at the data center in response to thepredicted value for the amount of stored power.